Optimal Designing of Permanent Magnet Cavity to Reduce Iron Loss of Interior Permanent Magnet Machine

The iron loss of the interior permanent magnet (PM) machine is larger when the machine runs at a higher speed. The great stator and rotor iron loss have a negative effect on the machine, so the PM cavity of the interior PM machine with a single-layer U-shaped PM geometry is improved to reduce the iron loss of the machine in this paper. Meanwhile, the Taguchi method is utilized to optimize the improved PM cavity at the rated point, maximum torque point, and flux-weakening point, respectively. The effects of each optimization variable on the iron loss and electromagnetic torque of the machine are analyzed. Then, the optimization scheme of the improved PM cavity is achieved at each selected operating point, respectively. The final optimization scheme of the improved PM cavity will be concluded after the overall consideration of optimization schemes at the selected operating points. In addition, the electromagnetic torque ripple and cogging torque are also effectively reduced by adopting the improved PM cavity, which improves the running stability of the machine.